there are local groups around most cities that have aya retreats (you could probably find them through reddit and/or discord). you basically meet up in someone's garage with a bunch of strangers and then puke in a bucket. or you can do more fancier ones in south america, which are obviously going to be more expensive (but might actually be able to better help or support someone with serious addiction issues).

Now, you used to be able to just buy ayahuasca analogs online, like acacia confusa + syrian rue; but they may have closed that loophole since then.

Note: I think a lot of these aya retreats have become more popular because they are classified as religious ceremonies; which SCOTUS upheld in 2006 for the use of magic mushrooms in native american practices

https://apnews.com/article/psychedelic-churches-ayahuasca-5101fe47fe9a6e28de686272ed96ff46